1. Technical Field
The present invention relates to a composite comprising titanium dioxide having photocatalytic activity and a pharmaceutical compound having drug efficacy, and particularly relates to a titanium dioxide composite with which a pharmaceutical compound is decomposed by photoexcitation of titanium dioxide to lose drug efficacy thereof. More particularly, the present invention relates to a method of treating a lesion by administering a dispersion to an animal including human, and subsequently irradiating a region surrounding the lesion.
2. Background Art
It is well known that a redox reaction occurs upon photoexcitation of titanium dioxide. In addition, titanium dioxide is used for foods and its safety has been confirmed to a certain level. It has been attempted that such titanium dioxide is administered in vivo to utilize its photocatalytic activity.
For example, WO2004/087765 proposes a titanium dioxide composite in which a molecule having molecular recognition ability binds to titanium dioxide through a hydrophilic polymer. It is attempted that this composite is introduced in a living body, then collected in a specific tissue or cells in the body by the molecule having molecular recognition ability, and irradiated with light to destroy the tissue or cells by the redox power of titanium dioxide. However, this WO publication does not disclose or suggest destruction of a molecule having molecular recognition ability itself supported in the composite by the redox power of titanium dioxide.
On the other hand, since some pharmaceutical compounds having specific drug efficacy such as anticancer drugs are often accompanied by adverse drug reactions, there is a technique with which a pharmaceutical compound is delivered only to an affected lesion but not to other healthy tissues or cells. This is a so-called drug delivery system (DDS) technique.
For example, for adriamycin, an anticancer drug, Japanese Patent Application Laid-Open Publication No. 7-69900, Japanese Patent Application Laid-Open Publication No. 5-955, Japanese Patent Application Laid-Open Publication No. 2-300133, and the like describe techniques combined with a polymer. However, improvement is still required in terms of efficient delivery to cancer cells, further suppression of adverse drug reactions and the like.
Further, Japanese Patent Application Laid-Open Publication No. 2002-316946 and Japanese Patent Application Laid-Open Publication No. 2002-316950 disclose a technique in which a drug, especially adriamycin, is supported on metal particles coated with titanium dioxide having photocatalytic activity and then introduced into cancer cells by a gene gun. It is said that when a drug is desired to be detoxified, the drug can be decomposed by a photocatalyst by UV irradiation in this technique. Since this technique premises the use of a gene gun, a special device, and a drug is supported by simple physical adsorption, however, there is room for improvement in terms of versatility and stability.